{"id":"CVE-2026-93857","kind":"vulnerability","aliases":["CVE-2026-93857"],"related":[],"title":"Fireware OS: SIP proxy buffer overflow lets unauthenticated remote attackers run code","description":"A stack-based buffer overflow vulnerability in Fireware OS's SIP proxy allows a remote, unauthenticated attacker to execute arbitrary code by sending a specially crafted request through a policy that uses the SIP proxy.","summary":"A stack-based buffer overflow in the SIP proxy of Fireware OS, the firmware for WatchGuard firewalls, can be triggered by a specially crafted request sent through a policy that uses the SIP proxy. A remote, unauthenticated attacker can execute arbitrary code on the appliance.","severity":"critical","cvss":9.2,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["firewall","fireware-os","infrastructure","network-appliance","sip","watchguard"],"not_affected_if":["no-sip-proxy-policy","patched-firmware"],"how_to_check":"- Check the installed Fireware OS version on the appliance (unknown for exact affected range; sources do not list it)\n- Check whether any firewall policy uses the SIP proxy (unknown; sources do not say how to see this in the UI)","fix":"- Move Fireware OS to a patched release (unknown; the sources do not name the fixed version)\n- Disable or remove firewall policies that use the SIP proxy until patched (inferred from the description; confirm with vendor advisory)","status":"open","published_at":"2026-10-27T16:17:32+00:00","first_seen_at":"2026-10-27T16:33:07+00:00","triaged_at":"2026-10-27T16:33:59+00:00","updated_at":"2026-10-27T16:33:59+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-27T16:33:59Z","model":"claude-haiku-5-5","output":{"fix":"- Move Fireware OS to a patched release (unknown; the sources do not name the fixed version)\n- Disable or remove firewall policies that use the SIP proxy until patched (inferred from the description; confirm with vendor advisory)","reach":"internet","title":"Fireware OS: SIP proxy buffer overflow lets unauthenticated remote attackers run code","impact":"high","summary":"A stack-based buffer overflow in the SIP proxy of Fireware OS, the firmware for WatchGuard firewalls, can be triggered by a specially crafted request sent through a policy that uses the SIP proxy. A remote, unauthenticated attacker can execute arbitrary code on the appliance.","category":"infrastructure","nicknames":[],"who_cares":["fireware-os","watchguard","firewall","sip","network-appliance"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker runs arbitrary code on the firewall appliance remotely","analyst_note":"Find the vendor advisory and NVD CPE data for the affected and fixed Fireware OS versions, and confirm whether the SIP proxy policy is the only trigger.","how_to_check":"- Check the installed Fireware OS version on the appliance (unknown for exact affected range; sources do not list it)\n- Check whether any firewall policy uses the SIP proxy (unknown; sources do not say how to see this in the UI)","needs_analyst":true,"not_affected_if":["no-sip-proxy-policy","patched-firmware"],"who_is_affected":"Organizations running WatchGuard Fireware OS firewalls with a policy that routes SIP traffic through the SIP proxy are exposed. Sites that do not use the SIP proxy in any policy, or that run a patched release, can skip it. The sources do not give the affected version range.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000661,"input_tokens":3306,"output_tokens":661,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-93857':15A,18A 'allow':88C 'applianc':26B,74B 'arbitrari':70B,95C 'attack':10A,67B,92C 'base':32B,78C 'buffer':5A,33B,79C 'code':12A,71B,96C 'craft':53B,101C 'cve':13A,16A 'execut':69B,94C 'firewal':19B,46B 'firewar':1A,21B,40B,83C 'fireware-o':20B 'firmwar':43B 'infrastructur':23B 'let':7A 'network':25B 'network-appli':24B 'os':2A,22B,41B,84C 'overflow':6A,34B,80C 'polici':58B,105C 'proxi':4A,38B,63B,87C,110C 'remot':9A,65B,90C 'request':54B,102C 'run':11A 'send':98C 'sent':55B 'sip':3A,27B,37B,62B,86C,109C 'special':52B,100C 'stack':31B,77C 'stack-bas':30B,76C 'trigger':49B 'unauthent':8A,66B,91C 'use':60B,107C 'vulner':81C 'watchguard':28B,45B","nicknames":[],"mitigations":[],"who_affected":"Organizations running WatchGuard Fireware OS firewalls with a policy that routes SIP traffic through the SIP proxy are exposed. Sites that do not use the SIP proxy in any policy, or that run a patched release, can skip it. The sources do not give the affected version range.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T16:17:32+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"5d1c2695-1a31-4499-88ae-e847036fd7e3","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-93857","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93857","severity":null,"published_at":"2026-10-27T16:17:32+00:00","modified_at":"2026-10-27T16:17:32+00:00","first_seen_at":"2026-10-27T16:33:07+00:00","fetched_at":"2026-10-27T16:33:07+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}